The present invention relates to the removal of cyanide from a fluid using hydrogen peroxide generated by combustion. The invention has particular applicability to the removal of cyanide from waste water generated during mining operations.
Mining operations, including gold mining, and other metal-extraction procedures can produce a large quantity of waste water containing cyanide. Since cyanide-bearing waste is too difficult to transport safely, the cyanide must be removed or detoxified in the vicinity of the mining site. A conventional method for removing cyanide from waste liquids is to oxidize the cyanide using hydrogen peroxide, as disclosed, for example, in U.S. Pat. Nos. 3,970,554 and 4,416,786. Residual amounts of cyanide remaining in a waste liquid thus treated can also be removed by bringing indigenous, cyanide-metabolizing microbes into contact with the waste fluid.
Unfortunately, hydrogen peroxide is not only expensive but also bulky, necessitating large tanks for its storage. Moreover, mining operations are frequently conducted at remote sites, to which transporting hydrogen peroxide is costly. In addition, the effectiveness of cyanide-removing microbes, upon which conventional mining operations heavily rely, is hampered, especially in colder environments, by a paucity of organic material which the microbes can use as carbon sources.
Accordingly, there is a need for more effective methods and systems for removing cyanide from waste fluid, particularly in the context of mining operations.